A typical wellhead structure for an oil and gas well includes a high-pressure wellhead housing secured to a low-pressure housing, such as a conductor casing. The wellhead structure supports various casing strings that extend into the well. One or more casing hangers are typically landed in the high-pressure wellhead housing, with each casing hanger being located at the upper end of a string of casing that extends into the well. A tubing hanger is also typically landed in the wellhead or a tubing head. A string of production tubing is supported by the tubing hanger. The production tubing extends through the production casing and provides a path for conveying production fluids from the formation to the wellhead. The area between the production tubing and the production casing is referred to as the annulus.
An oil/gas well also typically includes a production tree (also referred to as a Christmas tree) that is mounted on the high-pressure housing. The production tree includes a main production bore. Production bore stabs are commonly positioned between the main production bore of a production tree and the production bore of the tubing hanger so as to provide a flow passageway between those two production bores. This arrangement permits the production bore of the production tree and the production bore of the tubing hanger to be fluidly isolated from other bores and passageways within the completion system.
FIGS. 1-4 depict various aspects of one illustrative example of a prior art two-piece production/annulus bore stab 10. FIG. 2 is a cross-sectional view of the prior art production/annulus bore stab 10 taken through the axial length of the production/annulus bore stab 10. FIGS. 3 and 4 are transverse cross-sectional views of the production/annulus bore stab 10 taken where indicated in FIG. 1. As shown in these drawings, the prior art production/annulus bore stab 10 generally comprises an inner production stab body 11, an outer annulus stab body 12, an annulus T-ring 13, an annulus metal seal 14 and an annulus seal retainer 15. The production/annulus bore stab 10 also comprises a secondary annulus spacer 16, a secondary metal seal 17, a spacer 18, a primary metal seal 19 and a primary seal retainer 20. Also depicted is a set screw 21, a lower head cap screw 22, a set screw 23, a plurality of upper flow openings 24, a plurality of lower flow openings 25 and a plurality of flow channels 26. In general, the set screw 21 secures the annulus seal retainer 15 in position with respect to the outer annulus stab body 12 so as to secure the secondary metal seal 17 in position. The primary seal retainer 20 is adapted to be threadingly coupled to the inner production stab body 11 to retain the primary metal seal 19 in position and thereby provide a seal between an end 12A of the outer annulus stab body 12 and the outer surface 11A of the inner production stab body 11.
As shown in FIGS. 3 and 4, the outer surface 11A of the inner production stab body 11 has a plurality of channels or recesses 26 formed therein. When the inner production stab body 11 is positioned within the outer annulus body 12, a plurality of individual fluid flow paths 27 are defined between the recesses 26 and the inner surface 12B of the outer annulus stab body 12. Each of these fluid flow paths 27 is in fluid communication with one of the upper openings 24 and one of the lower openings 25.
The present application is directed to various embodiments of an improved one-piece production bore stab with integral flow paths.